1. Field of the Invention
The present invention relates to security systems and, more particularly, to an advantageous new system involving methods and apparatus for automated screening of security cameras, as in large-scale security CCTV (Closed Circuit Television) systems.
2. Prior Art
Security systems, as used for example in parking garages, provide one of the few areas where an owner may feel that it is necessary to employ installed security technology to its full capacity. When a security system is installed there may be implicit acknowledgment of the need for reliable dependence on the system and its functioning to full capacity. Its presence implies to the public that they are under the protection of the system. If then there is an event of loss or injury that might have been prevented had the system been functioning properly and to its full capacity, the owner may be confronted with a claim difficult to defend.
Although parking garages provide a valuable benefit and highly desirable or necessary service to the public by offering parking facilities for vehicles of members of the public, they may nevertheless present risk to members of the visiting public. Property crimes which have been committed in parking garages include auto vandalism and auto burglary; crimes against persons which have been committed in parking garages include purse snatching, strong-arm robbery and, occasionally, assault and abduction. Multi-level pay garages with tollbooths may offer crime deterrence because of access control and the requirement to pass a tollbooth upon exit. But even parking garages so equipped may be increasingly subject to risk of auto thefts and auto burglaries when these garages are located adjacent to quick escape routes such as freeway on-ramps or major thoroughfares.
CCTV systems can be an effective security tool when installed and operated properly as part of security systems in such premises where operators of parking garages have a duty to avoid crimes or other losses or injuries which might otherwise occur. Parking garages, in particular, are good candidates for CCTV coverage because persons are more likely to be alone and vulnerable than in the higher traffic areas. For a CCTV system to operate at full capacity, cameras of the system should be monitored at all times by security personnel.
A CCTV system of multiple video cameras in a parking garage conventionally has no auxiliary system to make intelligent decisions about which camera should be viewed on display monitors. But, it is submitted in accordance with the present disclosure, decisions about which camera should be watched, and which to ignore could instead be based on the content of the video, and electronic auxiliary circuits could be employed to provide intelligent decisions about which camera should be viewed on one or more selected display monitors. Furthermore, the intelligent system would be compatible with existing CCTV systems.
Although reference is made herein to garages, garages are only one example of premises at, in, or in connection with, which such premises security systems are employed to avoid crimes, losses, injuries or other undesired occurrences. Merely one example of an undesired occurrence (which may also be referred to an incidence) is unauthorized entry, and examples of unauthorized entry are typified by vehicular and pedestrian movement in an improper direction or through an unauthorized portal, space, lane or path. All such premises, whether commercial, governmental, institutional or private, in which a security systems or security device or apparatus of the invention could be employed, will be referred to herein as secured premises.
Small-Scale Security Systems
A small CCTV system may for example have a few cameras and a display monitor for each camera. A single security operator can have a continuous view of all the monitors, so that the sole operator can assess unusual events in a few seconds while watching the monitors, at least while carefully observing the monitors. Yet, even in a small system, it is difficult or impossible for one such person to watch the same scene or scenes continuously. After a few minutes of the same view, what may be termed attention fatigue sets in. After hours on duty, the monitors become to the security person just part of the background clutter. Thus, operator concentration and ability to discern undesired occurrences, which may otherwise be evident from the monitor displays, is reduced or lost.
Large-Scale Security Systems
In a large CCTV system having hundreds of cameras, the fatigue factor is extreme for security personnel who must observe a correspondingly large number of display monitors. Conventional CCTV control systems have been proposed which have capability to sequence cameras to monitors in rotation. This allows operators to view every camera in the system periodically with a reasonable number of monitors.
For example, in a large, sophisticated metropolitan system having about 300 CCTV cameras in garages, 13 security personnel might be needed to view every camera monitor once per minute, even when using a known sequencing system capable of switching four monitors per operator each 10 seconds. In such a system, presenting one view per minute on a display monitors will not allow operators to detect quickly occurring events such as purse snatching. In order to operate 13 security positions 24 hours per day, adequate staffing requires about 65 persons on staff. Even if resultant high costs of such staffing are sustainable, security personnel cannot practically be expected to maintain a satisfactorily high level of attention for adequate incidence discernment, because such personnel are presented on the display monitors with some 11,520 individual scenes to evaluate during each 8-hour shift.
Another known method of handling large numbers of CCTV cameras is to create a “wall of monitors.” Using, in a CCTV system of approximately 300 monitors, each of 19-inch type, stacked from a point beginning 3 feet above floor level and extending to 9 feet above floor level, a reach of approximately 137 feet of linear wall space would be required by the wall of monitors. Or, if arranged peripherally along the walls of a room, such monitors would completely line a room of dimensions 14 feet by 60 feet. If operators were stationed 20 feet apart along the wall (or walls), all camera views could be viewed on the display monitors by at least eight security personnel. However, if such a wall of monitors 137 feet in length were to be employed, it is improbable that any crime event or other incident would be seen.
FIG. 1 depicts a human figure, being that of a male 6 ft. in height, standing at one end of a row of 76 equipment racks holding 304 monitors, in order to simulate the appearance and relative scale of a so-called wall of monitors which would result from this large number of CCTV display monitors. Although the human figure is not drawn to scale, the operating viewing situation or requirements for such a wall of monitors can easily be visualized, and will readily be realized as being impractical for a large quantity of monitors. Smaller display monitors require less space, but security personnel must then view the smaller display monitors from a reduced distance, in order to be able to discern each scene.
It is postulated that the number of security personnel operators for watching display monitors of a large CCTV-equipped security system can be reduced by using known video motion detectors in combination with electronics for controlling CCTV switching. However, at some level of activity in garages of such a large security system using known video motion detection techniques, cameras without some detectible motion in the video are omitted from a switching sequence. While detection by a video motion detector of the movement of even a single car in a camera view would cause that camera to be included in the sequence, that same car driven by a person looking for a parking spot may pass several cameras, causing the view from each in turn to be presented on an operator's call-up screen.
Adding motion detection to every camera, and custom software to limit cameras in the sequence to those with motion could reduce the required staff watching cameras significantly. Although no precise data is known, it is estimated that operator attention requirements, which may be termed operator load, would decrease by a factor of two if only the cameras with motion were presented to operators of the system. Decreasing operator load by one-half would nevertheless require six operators on duty during the day, that is, as one shift, which would requiring a total operator staff of about 30 persons. Even if the security budget will allow for payment of 30 salaries for operating personnel, the monitoring task would drive these operators to extreme attention fatigue within any given shift.
A previously proposed CCTV system intended to be used with airport parking garages was premised on providing video motion detection on each video camera and using software to control electronic selection of only cameras providing video output with motion so as to be viewed by security operators. As the number of cameras in the proposed system was postulated to grow, the weakness of simple motion detection could become apparent. Commercially available motion detectors for such a system are found to be unable to distinguish a person from a vehicle. Thus, for example, every car passing by a camera could trigger a motion detector of the system. As vehicles would drive down aisles they would pass several cameras, and this would result in the presentation on display monitors of multiple views of the same vehicle. About six operators would be required to be on duty during the day, and the repetitive presentation of views caused by movement of a single vehicle past multiple cameras would cause extreme boredom and resulting lack of attention.
One known method of monitoring a scene is provided in Ross, U.S. Pat. No. 5,880,775, where pixels of individual frames are compared to generate a difference value, which value when exceeds a predetermined threshold activates a VCR (Video Cassette Recorder) for recording. Another method is provided in Winter et al., U.S. Pat. No. 5,875,305, where video data is analyzed to detect a predetermined characteristic based on features of a target such as size, speed, shape, or chrominance changes and subsequent video compression storage. Other methods of motion detection, fire detection, and other event-based detection with subsequent system action for security purposes are numerous and well known in the field. However, the known art does not fully address the need for intelligent camera selection based on a plurality of inputs for decreasing operator load and fatigue. Additionally, the known art does not control CCTV switching for operator viewing. Shiota et al., U.S. Pat. No. 4,943,854, provides a multi-video recorder that allows selection of a signal from a plurality of cameras, however, without any image analysis and based primarily on motion detection sensors. Furthermore, the known art detection methods do not employ the unique image analysis techniques of the present invention for intelligent camera selection, which are more fully described herein below.
Accordingly, a need exists in the art for image analysis techniques which are much more simplified. Simplified image analysis techniques will further allow for real-time image analysis and a more robust security camera screening system.